The present invention relates generally to communication networks, and more specifically, to discovering a circuit having different types of connections.
Today, SONET/SDH is the predominant technology for transport in worldwide public carrier networks. A SONET/SDH network includes nodes (network elements) interconnected by links. A network circuit can traverse one or more network elements. Each intermediate NE performs a cross connect function connecting the circuit data from one link to another to deliver data to the circuit destination. Creation of a multi-node SONET or SDH circuit requires the establishment of connections at source, destination, and intermediate nodes. Service providers often bypass a vendor's network manager application and connect directly to each network element in the circuit path to create the circuit cross connections. A network management interface may then be used to splice these individual connections to represent the complete end-to-end circuit. Aggregating the individual cross-connections into an end-to-end circuit is important to network management. This information is used for displaying and editing circuit properties such as direction, protection type (e.g., 1+1, UPSR, BLSR) and circuit end-points. Service providers therefore require the vendor's network management system to recognize such cross-connections and represent them as a complete end-to-end circuit.
Conventional circuit aggregation algorithms typically require that the cross-connections are the same type and size. For example, STS-1 connections can only be spliced with STS-1 connections, VT1.5 connections can be only be spliced with VT1.5 connections, VC4 connections can only be spliced with VC4 connections, and VC11 connections can only be spliced with VC11 connections.
Many high-order (HO) types of cross-connections are designed to carry multiple low-order (LO) paths. For example, a STS-1 path is designed to carry 28 VT1.5 paths and a VC4 path is designed to carry three VC3 paths. A high-order path (or cross-connection) transporting multiple low-order paths is referred to as low-order tunneling or low-order aggregation. Low-order tunnels (LOTs) and low-order aggregation points (LAPs) are commonly used by customers to optimize low-order matrix utilization, which implies creating low-order connections at the source and destination nodes of the circuit and high-order connections in the intermediate nodes.
FIG. 1 illustrates an example of a low-order circuit tunneling through high-order connections. The circuit includes a source node A, destination node D, and intermediate nodes B and C. The source and destination nodes may have VT connections and the intermediate nodes may have STS connections, for example. In this sequence of connections, the low-order circuit/traffic path is complete between the source and destination low-order connections, even though the connection types are different between the source and intermediate nodes. Conventional algorithms do not recognize this circuit as a single circuit, but instead as a set of three circuits: (1) the low-order connection at node A forms one circuit; (2) the intermediate high-order connections (nodes B and C) splice together to form one high-order circuit; and (3) the low-order connection at node D forms one circuit.
There is, therefore, a need for a method and system for representing low-order circuits using high-order paths as a single circuit so that a circuit having connections of different connection types can be discovered and managed.